1. The Field of the Invention
The present invention relates to valves. More particularly, this application relates to hemostasis valves for use in medical procedures.
2. Relevant Technology
Various medical procedures require temporary and often repeated introduction and removal of catheters and/or guide wires within the cardiovascular system of a patient. For example, using only a relatively small incision, a catheter can be introduced into a blood vessel of a patient and used to implant a stent or deliver a fluid directly to a predetermined location within the cardiovascular system. Catheters can also be used for exploratory surgery and for removing tissue samples within a patient's body.
Operations using catheters can often require the insertion and removal of several different types of catheters and guide wires, which can be employed to guide catheters to a desired location within the body. One of the problems encountered with the insertion, removal and adjustment of catheters and guide wires is controlling bleeding at the point where the catheters and guide wires are first introduced into the cardiovascular system.
In one approach to controlling bleeding and ensuring easy insertion and removal of the catheter and/or guide wire within the cardiovascular system, one end of a hollow introducer is first secured within a large blood vessel of a patient. The opposite end of the introducer is positioned outside the body of the patient and is attached to an adapter.
Such an adapter typically comprises a short, rigid tube having a passageway extending therethrough. Attached at one end of the adapter tube is a connector. The connector is used to connect the passageway of the adapter tube to the exposed end of the introducer. This enables fluids and/or medical instruments, such as catheters and guide wires, to pass between the adaptor tube and the introducer.
Positioned at the opposite end of the adaptor tube from the connector is a valve commonly referred to as a hemostasis valve. The hemostasis valve typically includes a seal positioned within a valve body. During use of the adaptor, the pressure of the blood of the patient caused by the beating of the patient's heart can cause blood from the patient to flow through the introducer and into the passageway of the adaptor tube. The seal is designed to prevent blood from escaping out of the adaptor.
One typical hemostasis valve is a "slit" valve. Another typical hemostasis valve is known as a "Touhy Borst" valve. Such a valve typically includes an elastomeric membrane having a passageway therethrough through which a catheter can extend. The elastomeric membrane can be selectively compressed about the exterior surface of a catheter to thereby establish hemostasis.
One increasingly common use for catheters is in the strategic placement of small balloons that can be selectively inflated within a blood vessel. The balloons are used for opening blood vessels that have been blocked or partially blocked by fat build-up. This opening or altering of the blood vessel is referred to as angioplasty.
Sometimes during angioplasty an expandable stent is mounted on a balloon catheter. The stent/balloon catheter assembly is guided through an adaptor into a blood vessel until reaching a particular portion of the vessel. Upon reaching the desired location, the balloon is inflated, thereby expanding the stent. The balloon is then deflated, separating the balloon from the expanded stent. The stent then remains in the blood vessel, thereby retaining the blood vessel in an expanded position, and the balloon catheter is removed from the blood vessel.
Stents may have a variety of different designs and may be implanted into blood vessels through a variety of different methods. Typically, stents are initially inserted through an adaptor, then inserted further into the blood vessel.
During such insertion, the stents are inserted through the hemostasis valve of the adaptor. However, unprotected stents are often damaged by the tortuous path travelled when pushed through a hemostasis valve. Stents, which are often relatively delicate, malleable structures, may snag on the valve or may be otherwise blocked or damaged by the valve. Unprotected balloons and stents can be caught in typical hemostasis valves and can thereby become dislodged or deformed.
According to one method for protecting a stent while inserting the stent through a hemostasis valve, the stent is placed within a catheter which is then inserted through the hemostasis valve and further into the cardiovascular system of the patient. However, this typically requires the use a separate catheter.
According to another method for protecting a stent, the hemostasis valve is first removed from the adaptor. The stent is then placed in the adaptor body and the valve is threaded back onto the adaptor behind the stent. This approach, however, is cumbersome and can result in the contents of the hemostasis valve being spilled during a medical procedure.
According to another method, an integral introducer is movably coupled within the valve and selectively opens a slit valve. However, such valves are typically designed to apply a set, predetermined amount of sealing pressure on a particular elongate instrument in an attempt to establish hemostasis. If the practitioner desires to increase or decrease the sealing pressure on a catheter or other instrument, the practitioner is required to employ a different valve which has a tighter or looser seal. This may require the practitioner to purchase and store a number of different valves for use during a particular procedure or with catheters having varying sizes.
There is therefore a need in the art for an improved hemostasis valve which enables an instrument to be protected while passing through the valve. There is also a need in the art for a hemostasis valve which does not limit a practitioner to a set, predetermined amount of sealing pressure which the practitioner can apply to a particular elongate medical instrument.